These month tokens are used to display a full-length form of the current month name.
All three of the above tokens give the same result; the only difference is the capitalization.
For example, on November 10, in English:
•[mmmm] = october.
•[Mmmm] = October.
•[MMMM] = OCTOBER.
In some languages, German for example, the first letter of all month names is always capitalized. It is always better to capitalize the token translation (ie. November) rather than the token [Mmmm] because it allows you to use the same GridTemplate for other languages where the first letter is not necessarily capitalized, such as Italian.